3,028 research outputs found
Size distributions of sprays produced by violent wave impacts on vertical sea walls
When a steep, breaking wave hits a vertical sea wall in shallow water, a flip-through eventmay occur, leading to the formation of an up-rushing planar jet. During such an event, a jet of water is ejected at a speed many times larger than the approaching wave's celerity. As the jet rises, the bounded fluid sheet ruptures to form vertical ligaments which subsequently break up to form droplets, creating a polydisperse spray. Experiments in the University of Hokkaido's 24m flume measured the resulting droplet sizes using image analysis of high-speed video. Consideration of the mechanisms forming spray droplets shows that the number density of droplet sizes is directly proportional to a power p of the droplet radius: where p=-5/ 2 during the early break-up stage and p=-2 for the fully fragmented state. This was confirmed by experimental observations. Here, we show that the recorded droplet number density follows the lognormal probability distribution with parameters related to the elapsed time since the initial wave impact. This statistical model of polydisperse spray may provide a basis for modelling droplet advection during wave overtopping events, allowing atmospheric processes leading to enhanced fluxes of mass, moisture, heat and momentum in the spray-mediated marine boundary layer over coasts to be described
Inferring Population Preferences via Mixtures of Spatial Voting Models
Understanding political phenomena requires measuring the political
preferences of society. We introduce a model based on mixtures of spatial
voting models that infers the underlying distribution of political preferences
of voters with only voting records of the population and political positions of
candidates in an election. Beyond offering a cost-effective alternative to
surveys, this method projects the political preferences of voters and
candidates into a shared latent preference space. This projection allows us to
directly compare the preferences of the two groups, which is desirable for
political science but difficult with traditional survey methods. After
validating the aggregated-level inferences of this model against results of
related work and on simple prediction tasks, we apply the model to better
understand the phenomenon of political polarization in the Texas, New York, and
Ohio electorates. Taken at face value, inferences drawn from our model indicate
that the electorates in these states may be less bimodal than the distribution
of candidates, but that the electorates are comparatively more extreme in their
variance. We conclude with a discussion of limitations of our method and
potential future directions for research.Comment: To be published in the 8th International Conference on Social
Informatics (SocInfo) 201
Contents lists available at ScienceDirect Forest Ecology and Management
journal homepage: www.elsevier.com/locate/foreco Effect of early age woody and herbaceous competition control on wood propertie
Letters and records of the dissenting congregations: David Crosley, Cripplegate and Baptist Church life
The original publication is available at www.springerlink.comInternational audienceThis chapter examines the status and function of letters in manuscript records of dissenting Churches of the post-Toleration years, concentrating on the correspondence of the Baptist Church of Cripplegate. The letters are placed in the context of controversies about Church government and discipline and the rhetoric used during the scandal caused by the excommunication of its Northern minister David Crosley for drinking, lying and adultery is assessed. In doing so, the chapter pays particular attention to the epistolary exchanges between metropolitan and provincial congregations and to what they reveal about conceptions of the Baptist ministry
Mechanics of the exceptional anuran ear
The anuran ear is frequently used for studying fundamental properties of vertebrate auditory systems. This is due to its unique anatomical features, most prominently the lack of a basilar membrane and the presence of two dedicated acoustic end organs, the basilar papilla and the amphibian papilla. Our current anatomical and functional knowledge implies that three distinct regions can be identified within these two organs. The basilar papilla functions as a single auditory filter. The low-frequency portion of the amphibian papilla is an electrically tuned, tonotopically organized auditory end organ. The high-frequency portion of the amphibian papilla is mechanically tuned and tonotopically organized, and it emits spontaneous otoacoustic emissions. This high-frequency portion of the amphibian papilla shows a remarkable, functional resemblance to the mammalian cochlea
Necrosis correlates with high vascular density and focal macrophage infiltration in invasive carcinoma of the breast
Necrosis is a common feature of invasive carcinoma of the breast and is caused by chronic ischaemia leading to infarction. Although necrosis was previously assumed to be due to a generally poor blood supply in the tumour, in this study we show that it is present in tumours with focal areas of high vascular density situated away from the actual sites of necrosis. This may account, in part, for the previous observation that necrosis is linked to poor prognosis in this disease. Highly angiogenic tumours often display blood vessel shunting from one tumour area to another, which further exacerbates ischaemia and the formation of tumour necrosis. We have recently demonstrated that high focal microphage infiltration into breast tumours is significantly associated with increased tumour angiogenesis and poor prognosis and that the macrophages accumulate in poorly vascularized, hypoxic areas within breast tumours. In order to investigate the interactions of macrophages with chronic ischaemia (as reflected by the presence of necrosis) and angiogenesis in breast tumours, we quantified the levels of these three biological parameters in a series of 109 consecutive invasive breast carcinomas. We found that the degree of tumour necrosis was correlated with both microphage infiltration (Mann–Whitney U, P-value = 0.0009; chi-square, P-value = 0.01) and angiogenesis (Mann–Whitney U P-value = 0.0008, chi square P-value = 0.03). It was also observed that necrosis was a feature of tumours possessing an aggressive phenotype, i.e. high tumour grade (chi-square, P-value < 0.001), larger size (Mann–Whitney U, P-value = 0.003) and low oestrogen receptor status (Mann–Whitney U, P-value = 0.008; chi-square, P-value < 0.008). We suggest, therefore, that aggressive tumours rapidly outgrow their vascular supply in certain areas, leading to areas of prolonged hypoxia within the tumour and, subsequently, to necrosis. This, in turn, may attract macrophages into the tumour, which then contribute to the angiogenic process, giving rise to an association between high levels of angiogenesis and extensive necrosis. © 1999 Cancer Research Campaig
The importance of transdiagnostic symptom level assessment to understanding prognosis for depressed adults: analysis of data from six randomized control trials
Background: Depression is commonly perceived as a single underlying disease with a number of potential treatment options. However, patients with major depression differ dramatically in their symptom presentation and comorbidities, e.g. with anxiety disorders. There are also large variations in treatment outcomes and associations of some anxiety comorbidities with poorer prognoses, but limited understanding as to why, and little information to inform the clinical management of depression. There is a need to improve our understanding of depression, incorporating anxiety co-morbidity, and consider the association of a wide range of symptoms with treatment outcomes. /
Method: Individual patient data from six RCTs of depressed patients (total n=2858) were used to estimate the differential impact symptoms have on outcomes at three post intervention timepoints using individual items and sum scores. Symptom networks (Graphical Gaussian Model) were estimated to explore the functional relations among symptoms of depression and anxiety and compare networks for treatment remitters and those with persistent symptoms to identify potential prognostic indicators. /
Results: Item-level prediction performed similarly to sum scores when predicting outcomes at 3 to 4 months and 6 to 8 months, but outperformed sum scores for 9 to 12 months. Pessimism emerged as the most important predictive symptom (relative to all other symptoms), across these time points. In the network structure at study entry, symptoms clustered into physical symptoms, cognitive symptoms, and anxiety symptoms. Sadness, pessimism, and indecision acted as bridges between communities, with sadness and failure/worthlessness being the most central (i.e. interconnected) symptoms. Connectivity of networks at study entry did not differ for future remitters vs. those with persistent symptoms. /
Conclusion: The relative importance of specific symptoms in association with outcomes and the interactions within the network highlight the value of transdiagnostic assessment and formulation of symptoms to both treatment and prognosis. We discuss the potential for complementary statistical approaches to improve our understanding of psychopathology
Evaluation of SLC11A1 as an inflammatory bowel disease candidate gene
BACKGROUND: Significant evidence suggests that a promoter polymorphism withinthe gene SLC11A1 is involved in susceptibility to both autoimmune and infectious disorders. The aim of this study was to evaluate whether SLC11A1 has a role in the susceptibility to inflammatory bowel disease (IBD) by characterizing a promoter polymorphism within the gene and two short tandem repeat (STR) markers in genetic proximity to SLC11A1. METHODS: The studied population consisted of 484 Caucasians with IBD, 144 population controls, and 348 non-IBD-affected first-degree relatives of IBD patients. IBD subjects were re-categorized at the sub-disease phenotypic level to characterize possible SLC11A1 genotype-phenotype correlations. Polymorphic markers were amplified from germline DNA and typed using gel electrophoresis. Genotype-phenotype correlations were defined using case-control, haplotype, and family-based association studies. RESULTS: This study did not provide compelling evidence for SLC11A1 disease association; most significantly, there was no apparent evidence of SLC11A1 promoter allele association in the studied Crohn's disease population. CONCLUSION: Our results therefore refute previous studies that have shown SLC11A1 promoter polymorphisms are involved in susceptibility to this form of IBD
Measuring the effect of enhanced cleaning in a UK hospital : a prospective cross-over study
Increasing hospital-acquired infections have generated much attention over the last decade. There is evidence that hygienic cleaning has a role in the control of hospital-acquired infections. This study aimed to evaluate the potential impact of one additional cleaner by using microbiological standards based on aerobic colony counts and the presence of Staphylococcus aureus including meticillin-resistant S. aureus. We introduced an additional cleaner into two matched wards from Monday to Friday, with each ward receiving enhanced cleaning for six months in a cross-over design. Ten hand-touch sites on both wards were screened weekly using standardised methods and patients were monitored for meticillin-resistant S. aureus infection throughout the year-long study. Patient and environmental meticillin-resistant S. aureus isolates were characterised using molecular methods in order to investigate temporal and clonal relationships. Enhanced cleaning was associated with a 32.5% reduction in levels of microbial contamination at handtouch sites when wards received enhanced cleaning (P < 0.0001: 95% CI 20.2%, 42.9%). Near-patient sites (lockers, overbed tables and beds) were more frequently contaminated with meticillin-resistant S. aureus/S. aureus than sites further from the patient (P = 0.065). Genotyping identified indistinguishable strains from both handtouch sites and patients. There was a 26.6% reduction in new meticillin-resistant S. aureus infections on the wards receiving extra cleaning, despite higher meticillin-resistant S. aureus patient-days and bed occupancy rates during enhanced cleaning periods (P = 0.032: 95% CI 7.7%, 92.3%). Adjusting for meticillin-resistant S. aureus patient-days and based upon nine new meticillin-resistant S. aureus infections seen during routine cleaning, we expected 13 new infections during enhanced cleaning periods rather than the four that actually occurred. Clusters of new meticillin-resistant S. aureus infections were identified 2 to 4 weeks after the cleaner left both wards. Enhanced cleaning saved the hospital £30,000 to £70,000.Introducing one extra cleaner produced a measurable effect on the clinical environment, with apparent benefit to patients regarding meticillin-resistant S. aureus infection. Molecular epidemiological methods supported the possibility that patients acquired meticillin-resistant S. aureus from environmental sources. These findings suggest that additional research is warranted to further clarify the environmental, clinical and economic impact of enhanced hygienic cleaning as a component in the control of hospital-acquired infection
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